1. Field of the Invention
The present invention relates to a sheet storing apparatus, and more particularly to a sheet storing apparatus for stacking sheets discharged from an image forming apparatus, such as an electrophotographic machine and a laser printer, on a tray.
2. Description of Related Art
In a laser printer, occasionally a large number of sheets are printed in continuous printing operation, and therefore a type of sheet storing apparatus having a plurality of capacious stacking tables such as trays or stackers has been developed into various models to be provided for laser printers. Generally, such a sheet storing apparatus has a mechanism for moving down the stacking table intermittently with growth of a sheet stack on the table, and a mechanism for moving the stacking table horizontally at predetermined intervals to enable offset sheet stacking on the table. Further, the apparatus is so made that each sheet is transported onto one of the stacking tables selectively.
In the sheet storing apparatus, even when sheet jamming takes place near or on one of the stacking tables or when motor trouble occurs in one of the mechanisms, it is theoretically possible to continue sheet storing by using the other stacking tables. In conventional sheet storing apparatuses of this type, however, in such a situation, the whole system is run down to discontinue the sheet storing operation, and the printing operation in the image forming apparatus is also discontinued. In order to resume the operation, the operator must check the inside of the image forming apparatus and remove the jammed sheet from the apparatus, which is inconvenient. Also, when at least one of the mechanisms has motor trouble, the apparatus cannot be in a stand-by condition in spite of supply of electricity. In such a case, the apparatus must wait for repair of the motor by a serviceman.